The present invention relates generally to the field of mobile robots and in particular to articulated robot platforms comprising payload mounting assemblies, leg mounting assemblies and joints for combining leg assemblies, mobility elements for leg mounting assemblies including wheels, tracks, wheels and tracks, and to payload torsos in general including payload torsos with arms for lifting and extraction.
The invention relates to robotic configurations which assume humanoid forms where there is a head, torso, hips, and legs. The present invention further relates to drive systems for driving tracks and wheels and to drive systems for rotationally moving leg assemblies at their joints. The present invention further relates to drive elements and control systems for establishing dynamic stability for such an articulated robot in various postures.
Robots are often used to perform tasks that are inherently dangerous for humans. For example, robots have been used to explore dangerous caverns, disarm explosive devices, and identify chemical biohazards. This often requires remote or teleoperated maneuvering. The invention therefore relates to mobile robotic platforms that carry appropriate sensor systems for inspection, search, detection, and like and similar tasks. The invention then also relates to both autonomous and teleoperated controls and to sensors and controls for establishing the state of the environment surrounding the mobile robot for use with autonomous and teleoperation of mobile robots. Various teleoperated systems which are known in the art support such robotic platform control. For example, the software architecture disclosed in Allard U.S. Pat. No. 6,535,793. Information on the Joint Architecture for Unmanned Ground Systems (“JAUS”) can be found at http://wwwjauswg.org. This website features the definitive descriptions and publications for elements related to the JAUS standard.
Often, this application requires navigation over various terrains including terrains with rough and uneven surfaces. Therefore this invention relates to mobile robotic platforms comprising combinations of the above mobility elements including tracked mobility platforms, wheeled mobility platforms, and wheeled and tracked mobility platforms for navigating in such environments and to the combination of such mobility platforms with torsos enabled to lift heavy and non-rigid objects.
All-terrain, mobile robotic vehicles are known in and have been discussed extensively in the literature. Foster-Miller®, an engineering and technology development firm based in Waltham Mass. is developer of Talon™, an example of the current state of the art in a mobile tracked platform. Talon is capable of maneuvering over rough terrain, comprising a main platform with dual tracks. iRobot®, a robotic company based in Burlington, Mass., is developer of PackBot™. PackBot is a tracked mobility platform also capable of maneuvering over many kinds of rugged terrain, which comprises a main frame in combination with forward arms and can self-right itself if flipped over. In addition, PackBot as disclosed in the work of WON, U.S. Pat. No. 6,431,296, is also capable of navigating up stairs. U.S. Pat. No. 6,662,889 off De Fazio has similar structure but utilizes a wheeled platform. Therefore, the invention relates to tracked platforms with symmetrical configurations having main stages with parallel tracks and to platforms with untracked and/or tracked forward stages in combination with tracked main stages where the forward stage provides additional flexibility in self-righting and in stair traversal.
Robots are further used to lift and move objects which would be prohibitive or difficult to handle. This invention therefore relates to mobile robotic platforms which combine mobile platforms with lifting torso configurations capable of maneuvering, lifting, and conveying difficult to handle objects and in particular to robots capable of maneuvering when engaged in conveying such difficult to handle objects in tight spaces.
In addition, robots have been used for transporting heavy loads from one location to another including traversing various obstacles such as navigating stairs. For example in the work of CHEN U.S. Pat. No. 6,144,180 a mobile robot is provided for that can carry a heavy load from one location to another including up or down a flight of stairs using a dual wheel and tracked mobility platform.
Robots used for handling heavy loads have been configured with torsos and arms for cinematic enjoyment by the consumer. Robots with torsos, arms, and end effectors are deployed commercially in mobile postures where their operation on assembly lines provides for the manipulation of objects with difficult to handle shapes that also are characterized by having substantial weight, such as in the assembly line for automobiles, a field of practice in which robots with bases, having arms with end effectors and motion controllers enabling multiple degrees of freedom are deployed for various application specific tasks. The work of JOHNSON U.S. Pat. No. 5,394,766 provides for a robotic human torso deployed by Disney and the work of KROCZYNSKI U.S. Pat. No. 4,565,487 provided for a robot with legs or arms. Many others have provided controlled and balanced articulated platforms for industrial use. U.S. Pat. No. 4,024,961 (Stolpe) and U.S. Pat. No. 6,408,225 (Ortmeier et al.) are representative. Therefore the invention relates to robots with articulated torsos for the purpose of lifting and conveying difficult to handle objects and the invention relates to robotic torsos and robotic arms capable of lifting payloads of various weights.
The invention also relates to Dynamic Balancing Behavior (“DBB”) as a behavior that can be employed to enable mobile platforms carrying a payload to maneuver and navigate while maintaining a consistent and stable position of the center of gravity (dynamically stable) of their mobile platform while in motion. U.S. Pat. No. 6,527,071 (Villedieu) provides for a gyroscope stabilization mechanism in a two wheeled robot and, U.S. Pat. No. 6,330,494 (Yamamoto) provides a stabilizing system in which a playback technique is used to redeploy a posture in a feedback control loop. In Raibert, M. H., Legged Robots that Balance, MIT Press, Cambridge, Mass., 1986, an earlier use of this mechanism is disclosed.
Segway Inc. of Bedford N.H. has developed and marketed the Segway Human Transporter which utilizes dynamic stabilization to keep a human payload in an upright position while moving forward over regular terrain. KAMEN in U.S. Pat. No. 6,302,230 (Kamen et al.) and U.S. Pat. No. 6,779,621 disclose Dynamic Balancing Behavior (“DBB”) as a basis for stabilization of a personal mobility transporter. Therefore the invention relates to mobile platforms which employ dynamic balancing behavior to achieve stabilization in operation for achieving various maneuvering goals.
The known prior art presented provide publicly known solutions that advanced or now serve to advance the state of the art in mobile robotic platforms, but each known solution has readily observed problems or limitations. For example, U.S. Pat. No. 6,263,989 of Won shows a FIG. 8C (side view of FIG. 3a) as depicted here in FIG. 22 where MP is main platform and FP is forward platform.
FIG. 3a b and c show the robot 100 in a fully extended position. The main section incorporates a dual track configuration in which the side plates 312 are rigidly coupled by the tubes and articulator shaft. This portion of the construction results in “high pointing” (also known as “high topping” or “high centering”) in which a portion of the assembly can get stuck on an object whose height is taller relative to ground than the plane of the tubes and articulator shafts.
In U.S. Pat. No. 6,662,889 De Fazio, for example, FIG. 1b, FIG. 2, FIG. 1b discloses a wheeled embodiment of a robotic platform in which a front assembly is coupled to a main section. This platform is, in effect, a derivative of WON and suffers from the same limitations of WON. Although the device is comprised of an entirely wheeled mobility system, no other advantage is afforded the structure other than faster operation on normal terrain.
So, both these robots suffer from a common drawback. First, they are limited to being configured with solely tracks or solely wheels, thereby limiting the number of end uses the platform may serve. Further, both robots are designed for typical operation with a regular payload, but only when they are not burdened with a significant payload or one which is non-rigid. For these robots, having to carry such other forms of payloads can significantly complicate and fundamentally compromise their maneuverability and overall effectiveness.
In U.S. Pat. No. 614,418, Chen, for example in FIG. 3 presents a hybrid wheeled and tracked robotic platform in which the platform is designed for stair climbing while holding a payload of substantial and material substance. What is described is a vehicle that has a pair of lift arms and a pair of leg support arms. The ability to raise the tracked structure separately from the wheel permits a form of stair climbing in which the rotational posture of each of the track and wheel respectively “walk” along a surface or up a set of stairs, with each assembly respectively, rotationally taking a lead position, and by lifting the other set, ambulating in one direction or another, as shown in FIG. 6. FIG. 9 shows how the tracks can be stowed and wheeled motion can permit the navigation of an incline while keeping the payload balanced in an upright position. Each wheel and track subsystem is an integral device which permit the mobility that Chen delivers. In particular, a track is pivotally hinged with a single wheel on a transverse axis such that the track can be stowed up to permit the wheel to locomote, or placed down for balancing on a plane or stair.
What is provided for therefore, in Chen, is a vehicle that has a pair of lift arms and a pair of leg support arms. The ability to raise the tracked structure separately from the wheel permits a form of stair climbing in which the rotational posture of each of the track and wheel respectively “walk” along a surface or up a set of stairs, with each assembly respectively, rotationally taking a lead position, and by lifting the other set, ambulating in one direction or another, as shown in FIG. 6. FIG. 9 shows how the tracks can be stowed and wheeled motion can permit the navigation of an incline while keeping the payload balanced in an upright position. Each wheel and track subsystem is an integral device which permit the mobility that Chen delivers. In particular, a track is pivotally hinged with a single wheel on a transverse axis such that the track can be stowed up to permit the wheel to locomote, or placed down for balancing on a plane or stair. It is a limitation of Chen that the relationship of the wheel set and track set in a particular leg are at a fixed angular position, one with respect to the other, and rotate in unison when deployed for the Chen maneuvers. It is further noted that a limitation of Chen is that the payload must be placed on the mobile platform and conveyance is then elected as the next maneuver. Chen therefore has the limitation of not being able to both lift and convey a payload. The interlocked wheel and track mechanism of Chen has the further limitation of being limited to operating on a set of wheels or a horizontally deployed track which offers increased friction for applications in which more efficient or faster movement is desired.
With respect to platforms designed to operate in dynamically stable postures, the current art shows solutions where the underlying technology used by the Segway® has only been applied to transporters designed for easily navigable terrain in which the user starts from an upright posture, near dynamic balance with the purpose of maintaining such dynamic stability in forward motion at various speeds. Further, Segway®-like systems are designed for limited-purpose, human use, and are thus equipped with safety features that diminish the marvels of the underlying DBB technology. Among other limitations of present DBB platforms such as Segway® transporters are their need to maintain a strict vertical balance to avoid throwing their riders, and their need to restrict the maximum speeds for saftey and by law.
Although the above described devices represent advances over previous designs for mobile robot apparatus, the above referenced inventions have notable limitations. They are inefficient, poorly suited, and/or limited in their mobility when engaged in lifting and extraction and further are ineffective in operating in heterogeneous terrain that encompasses smoother more generally tractable expanses and expanses that comprise rough, uneven and unpredictable terrain, while still supporting the goal of lifting and extracting cumbersome and heavy objects.
Then, what is provided for in the present invention discloses a mobile apparatus that is unique and comprises a number of new aspects each of which individually operates to unexpectedly overcome the specific limitations mentioned above and which new aspects, when taken in various combinations, serve to not only overcome the limitations mentioned but further the “state of the application art” in mobile robot platforms with additional novel architectures for mobility as well as offering additional unexpected benefits in heretofore unaddressed end uses.
What is new in this invention is the deployment of a payload base as a hip assembly for allowing the attachment of a torso, in particular a torso for lifting heavy payloads, and for permitting the configuration of separate and parallel leg assemblies, each of which may be independently articulated, which leg assemblies each comprise independent upper and lower leg sections, which upper and lower leg sections, when respectively outfitted with mobility elements, themselves can each be independently driven to permit novel mobile operation. What is new in this invention is the provision of such a set of leg assemblies, where the mobility elements permit both a homogeneous configuration of an all tracked platform or an all wheeled platform, as well as hybrid configurations in which tracks are provided on upper leg sections and wheels on lower leg sections, or just tracks or wheels on lower leg sections, each of which configurations offers certain application specific advantages, the present advantage of which is unique to this invention, where the new feature offers the additional advantage of hybrid outfitting of a common dual legged platform. What is new in this invention is the addition of independent dynamic balancing control to each of the leg sections permitting maneuvers where dynamic stability is achieved and in particular to the ability to move from a statically balanced posture to a dynamically balanced posture with directional movement. The ability to offer this feature in a mobile platform of the form provided for in this invention is new and further, the ability to use dynamic balancing to move from a statically balanced position to a dynamically balanced position in conveyance maneuvers where the lifting and transfer of a payload is required is new. It is also new to provide the feature of dynamic balancing in a mobile platform as provided for in this invention as a preferred configuration for climbing stairs, navigating over rough terrain, and lifting a payload and maneuvering on stairs or over various other forms of terrain where the new feature is the way in which the leg sections can be articulated, powered, and balanced to achieve said application specific ends.
The opportunity to solve problems which prior tools in this space have as their limitations enables us to provide for an invention that relates to new ways to make a mobility platform that provides new and useful aspects which serve to overcome the limitations of the prior, publicly known solutions.
Therefore, the limitations of Won and DeFazio are overcome in the present invention by providing for the independently articulated upper leg assembly where the upper leg sections are pivotally connected to the payload base hip section, resulting in avoidance of high pointing caused by the rigid frame coupling the tracks together, where the rigid frame can impact with an object. Taken in combination with the rotational features of the knee joint which couple the upper leg and the lower leg, the present invention offers the unexpected advantage of avoiding high pointing. Further, in FIG. 8a-c Won depicts what is called “upright mobility mode” in which the mobile platform of Won can drive on the front track portion and move forward in “praire dog mode” where the robot balances the main body on the forward arms. It is noted that this is also the position where the center of gravity is in a position defined by the arco of the arms but “just short of a position in which the robot would topple”. Not only does this configuration have the limitation that no load bearing weight can be deployed or conveyed, if Won were in drive motion and hit any object, this impact alone would result in a toppling outcome and the robot would need to re-right itself in order to proceed in what is referred to as the upward mobility mode. WON has no mechanism to maintain balance when mobile if an obstacle is hit on uneven terrain. The apparatus of the present invention can operate in an upright mobility mode with the upper legs raised, and not only avoid obstacles that WON would be unable to avoid simply by the independent articulation of its legs in repositioning it's hip assembly to a higher plane. In addition, the apparatus of the present invention provides for increased stability in such an upright mode by maintaining dynamic stability using the dynamic balancing control system to establish a variety of mobility modes in both a fully loaded as well as an unloaded configuration, while maintaining upward stature when in motion over various terrains. In each of these dynamically stable postures, the apparatus of the present invention is able to establish the vertical projection of the center of gravity on the ground in a position within the footprint established by the contact point of the apparatus with the ground, thereby maintaining posture while moving over the ground.
The present invention provides for an improvement over De Fazio, where a fully wheeled platform is provided, by offering the independently articulated leg structure set forth above while further providing a structure in which each of the wheel sets may be driven separately and where the wheel sets, when driven, provide for mobility, as well as offering the option of movement in dynamic balance. Further, the present invention offers the option of fitting the upper leg section with a track, permitting a tracked method of achieving mobility by coupling the drive wheels with a track that is engaged in each of the wheels. This improvement enables a single robotic platform to be outfitted with either construction permitting a much larger application domain for deployment, for example, the ability to operate over rough and uneven terrain using the tracked section, and alternatively operating over smoother terrain more efficiently by using the wheeled sections.
The present invention overcomes the limitations inherent in Chen. With respect to Chen, a preferred embodiment of the present invention deploys an upper leg independently from a lower leg and therefore deploys, in at least one embodiment, a set of wheels independently from a set of tracks. Further, the present invention establishes its balancing control on either the footprint established by the tangent of the wheel or the tangent of the track or the tangent of the wheel and track, for drive movement forward, in reverse, or in a circle while using the full longitudinal articulation for increased speed and for more flexible mobility on a stair or over substantially similar obstacles. The present invention permits both structural support for lifting and provides for maneuvering in far more flexible ways and in a smaller locus, while operating at higher speeds in two wheel dynamic stability mode. The present invention overcomes the limitation in Chen in which the wheel and track are interlocked, by providing for upper and lower legs that can be articulated completely independently one from the other, as well as being controlled and driven independently, not only for providing for improved maneuverability, but also permitting operation on solely the tangent of either a set of wheels with the ground or on a tangent of a set of tracks with the ground, by integrating dynamic stability in the application of balancing, with or without a load, to permit the present invention faster and more efficient drive speeds as well as far more flexible operation with a payload including lifting, extraction, and deposition.
Further, what is new in this invention, which permits the present invention to overcome the limitations of Kamen and the way in which dynamic balancing is achieved in Segway and other like and similar conveyance devices, is that the present invention provides for dynamic stability control in combination with the joint articulation of the present dual independent leg mobility system, to enable the platform to move from a static to a dynamically balanced position, to do so while lifting a payload, and to maintain dynamic stability while in conveyance mode.
What is new with respect to stereotypical robot configurations that are provided for here is an invention in which a separately controlled and articulated upper/lower leg system is connected through rotational joints to a payload base hip section, providing for a novel structure for a mobility platform which eliminates the highpoint interference of a main platform section in the majority of maneuvers.
In particular, the invention delivers new ways to configure a mobility platform and ways to stabilize such a platform under no load and load conditions. This invention presents such a separately controlled and articulated upper/lower leg platform which further employs dynamic stabilization to permit additional forms of high speed maneuverability over a diverse set of terrains. Further, this invention provides for the above mentioned platform in combination with a torso capable of its own respective degree of freedom and which further enables lifting, maneuverability, and conveyance of a payload while preserving all of the flexibility enabled when unloaded. This invention further provides a hybrid wheeled and tracked robotic platform in which the platform is capable of maintaining a center of gravity in dynamic balance with the minimum point of ground contact established between the platform and ground, which also permits a second stair climbing maneuver while holding a payload of substantial and material substance. The invention further provides for motor hubs in which the drive system for the hub is contained within the within the hub and for wheeled configurations in which the hubs may be individually configured with tires or paired and coupled with tracks to permit a single mobile platform which can be deployed as solely wheeled, upper leg dual tracked and lower leg wheeled, or upper and lower leg dual tracked.
The present invention deploys a set of wheels independently from a set of tracks and establishes its balancing control on either the footprint established by the tangent of the wheel or the tangent of the track or the tangent of the wheel and track, for drive movement forward, in reverse, or in a circle while using the full longitudinal articulation for mobility on a stair or over substantially similar obstacles, permitting both structural support for lifting and maneuvering in far more flexible manner and in a smaller locus, all while operating at higher speeds.
So, the present invention is novel with respect to the structural configuration that uses tracked mobility elements and wheels as mobility elements in the basic manner in which such wheel and tracks are deployed as independently articulated members, and further, when combined with dynamic stability controls that permit the displacement of the center of gravity over a minimal footprint established by the contact of a portion of the mobility element with the ground, providing the ability of the mobile platform to move in yet additional maneuvers including rapid movement over a variety of terrains.